Fingerprinting Basics

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DNA fingerprint profiles are graphical representations of DNA fragment patterns. The fragments are generated in the laboratory.

Depending on the method used for fragment generation we can classify fingerprinting techniques as follows:

Type	Description
Fragmentation methods	The DNA molecules of a sample are broken into pieces (fragments) at certain locations. An example for a fragmentation analysis is the restriction fragment length polymorphism (RFLP) analysis. This method breaks the original DNA sample, e.g. an PCR-amplified gene sequence, at restriction enzyme recognition sites into pieces. A modification of the original RFLP technique is the terminal restriction fragment polymorphism (tRFLP).
Synthesis methods	The fragments are generated by synthesizing DNA fragments. This is usually done by PCR-related methods. The random amplified polymorphic DNA (RAPD) method uses the synthesis approach by amplifying DNA stretches that lie between the same two known sequence motifs (= random priming sites). Other synthesis methods are microsatellite and minisatellite analysis.
Mixed methods	The amplification fragment length polymorphism (AFLP) method uses restriction enzymes for fragmentation of whole genomic DNA and afterwards PCR-amplification steps to synthesize a subset of the generated fragments.